System goal first
Define what the organisation or value stream is trying to achieve and the measures that demonstrate progress.
Special Processes Institute
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Theory of Constraints Project Report
Theory of Constraints Project
Learn and apply the Theory of Constraints as a practical system for improving throughput, flow and delivery. Identify the system constraint, protect and exploit it, subordinate non-constraints, evaluate elevation options, design Drum-Buffer-Rope controls, record actions and evidence, assess organisational readiness, save or load projects as JSON, load a complete special-process example and create a professional PDF-ready report.
Focus the system Increase throughput Avoid local optimisation
TOC
Constraint-led improvement
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Constraint observations
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Open actions
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TOC readiness score
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Project completeness
What the Theory of Constraints Means
Improve the whole system by focusing on what limits its goal.
Theory of Constraints (TOC) is a management approach based on the principle that every goal-oriented system is limited by at least one constraint. Improving a non-constraint may create activity, inventory or local efficiency without improving overall performance. TOC therefore concentrates management attention on the factor that currently limits throughput, then repeats the cycle when the constraint moves.
IdentifyFind the system constraint
ExploitUse it effectively now
SubordinateAlign everything else
ElevateIncrease capacity or capability
RepeatPrevent inertia and find the next constraint
Throughput over activity
Work only creates throughput when the system delivers what the customer requires. Busy resources do not automatically create value.
One limiting factor
The active constraint may be equipment, labour, policy, supplier capacity, information, approval, demand or management attention.
Protect the constraint
The constraint should not be starved, blocked, interrupted by avoidable work or used for tasks that can be performed elsewhere.
Control release
Work should enter the system in line with constraint capacity and customer need, limiting excess WIP and hidden queues.
Repeat without inertia
After improvement, the former constraint may no longer be limiting. Controls and assumptions must be reviewed rather than preserved blindly.
Good TOC practice: defines the system boundary and goal; uses reliable flow data; distinguishes the true constraint from symptoms; protects safety and quality; improves constraint uptime and yield; controls WIP; measures throughput and lead time; and verifies that gains reach the customer.
Common failure modes: selecting the busiest machine without evidence, maximising utilisation everywhere, building excess buffer inventory, moving work without addressing policy constraints, elevating before exploiting, ignoring quality losses at the constraint and failing to identify the new constraint.
TOC Methods and Tools
Drum-Buffer-Rope
Drum
The constraint sets the pace for the system. Its schedule should reflect customer priorities, realistic capacity, setups, maintenance and expected losses.
Buffer
Time, material or capacity protection placed strategically so normal variation does not starve the constraint or jeopardise customer delivery.
Rope
The release signal that prevents work entering faster than the system can complete it. This limits WIP and exposes disruption earlier.
Core TOC Measures
| Measure | Meaning | Management question |
|---|---|---|
| Throughput | Rate at which the system generates value through completed customer demand. | Did the change increase completed, accepted and deliverable output? |
| Inventory / investment | Money and resources tied up in items intended for sale or delivery, including WIP. | Did WIP rise without increasing throughput? |
| Operating expense | Money spent turning investment into throughput. | Did the change reduce expense without harming throughput, quality or resilience? |
| Constraint utilisation | Useful constraint time producing conforming output against planned available time. | How much time is lost to starvation, blockage, setup, defects, breakdown or non-constraint work? |
| Buffer status | Protection remaining before the constraint or delivery commitment is threatened. | Which causes repeatedly penetrate the buffer? |
| Flow time | Elapsed time from release to completion. | Can less work be released while maintaining or improving delivery? |
TOC in Manufacturing, Quality and Special Processes
Important: TOC does not permit bypassing approved controls. A constraint-focused improvement must still protect safety, product conformity, process validation, configuration, statutory obligations and customer approvals.
Heat treatment
A qualified furnace may be the constraint. Improve loading readiness, schedule compatible cycles, protect maintenance windows and prevent avoidable rework without changing approved cycles.
Plating and anodising
The constraint may be tank capacity, rectifier capability, masking, laboratory release or final inspection. Control release and protect conforming first-pass yield.
NDT
Qualified personnel, equipment, technique approval or interpretation capacity may constrain flow. Remove non-value administration and prevent repeat examinations.
Welding
A qualified welder, fixture, inspection stage or engineering approval may be limiting. Keep constraint work ready and prevent defects consuming scarce qualified capacity.
Supplier quality
The constraint can be disposition, concession approval, FAIR review or a scarce external provider. Prioritise decisions by throughput impact rather than age alone.
Policy constraints
Batch rules, release approvals, performance targets or local utilisation measures can restrict flow even when physical capacity is available.
TOC Project Builder
IDENTIFY — Define the system0% complete
Constraint Evidence Register
Action Tracker
TOC Readiness Assessment
Score each question 0–4.
Scoring: 0 = absent; 1 = major gaps; 2 = partly effective; 3 = effective with minor gaps; 4 = robust, understood and sustained.
Complete the assessment to obtain guidance.
Theory of Constraints Project Report
Generated from the project, evidence, actions and assessment.
Complete the project and select Generate Report.